America's presidential primary season ends Tuesday after five months with contests in Montana and South Dakota. Hillary Clinton's campaign says she will not concede nomination to Obama Tuesday evening. As we hear from VOA's Cindy Saine, the so-called "superdelegates" will likely determine whether Democratic frontrunner Barack Obama will be able to claim the nomination.

Democratic presidential hopefuls Sen. Hillary Rodham Clinton (l) and  Sen. Barack Obama (file photo)

Senators Hillary Clinton and Barack Obama are vying for a total of 31 pledged delegates in Montana and South Dakota. Even if Obama wins both states as expected, that will not give him enough for an outright win of the Democratic nomination.

But the 46-year-old presidential hopeful is hoping to get the backing of more of the party elders and elected officials, the so-called "superdelegates." By most estimates, Obama needs the support of about 25 superdelegates out of the more than 150 that have still not announced their preference. All eyes are now on the superdelegates to see if a bloc of them comes out to endorse Obama, giving him the total number of delegates required to clinch the nomination.

Newsweek's senior Washington correspondent and columnist, Howard Fineman, says Obama is on the brink of victory. "Well, the most likely scenario is that by the end of this week Barack Obama will have wrapped up the Democratic nomination. It has been a long contest, one of the longest on record, and he is not crossing the finish line with a huge burst of energy but he is crossing the finish line ahead," he said.

Obama is planning a major address in Saint Paul, Minnesota, shortly before the polls close later tonight. It is not yet clear whether he will be able to use the venue to declare himself the Democratic nominee.

Hillary Clinton, who trails Obama by more than 150 delegates, will be addressing supporters in her home state of New York. There have been conflicting reports from inside the Clinton campaign about what she plans to say, but the campaign is insisting that she does not intend to suspend her campaign or end her candidacy Tuesday night. Fineman says Clinton will need more time to throw her support behind Obama.

"I don't expect her to endorse him immediately. I think it is going to take her a while to come to terms with the fact that she came so close but didn't get it. Don't forget, a year ago at this time she was the prohibitive favorite. She was on her way to a coronation, not a campaign. And she came very, very close here at the end," he said.

Clinton has won large, lopsided victories in several of the last primaries, including one Sunday in Puerto Rico, but it appears too late to change the dynamics of the race with Obama so far ahead in the delegate count.

On the Republican side, Arizona Senator John McCain has already been his party's presumptive nominee for months. He plans to try to steal a little of the spotlight from the Democrats Tuesday night by giving a speech on reform. Both parties will formally nominate their presidential choices at party conventions in late August and September.